The aircraft was hit by a missile fired form a Buk launcher, according to the adviser to Ukraine's interior minister, and the The New York Times reports that military and intelligence analysts are working to pin down the missile's point of origin.

U.S. President Barack Obama, Ukrainian President Petro Poroshenko and Malaysian Prime Minister Najib Razak have responded to the tragedy, promising to investigate.

Poignant images of the crash site show what's left of the plane. In the photo above, people near the village of Grabovo inspect debris from the plane, which was reportedly flying at an altitude of 33,000 feet when it was shot.

Dominique Faget / AFP / Getty

A piece of the aircraft lies in a wheat field in Eastern Ukraine, near the Russian border. Poroshenko denied any involvement in the crash, saying, "We do not exclude that this plane was shot down, and we stress that the Armed Forces of Ukraine did not take action against any airborne targets."

Dominique Faget / AFP / Getty

Luggage aboard Flight MH17 survived the crash of the Boeing 777 aircraft, which was heading from Amsterdam to Malaysia's federal capital, Kuala Lumpur.

Dominique Faget / AFP / Getty

After learning of the crash, Obama said the U.S. government's "first priority" is to determine whether any Americans were onboard the flight. "It looks like it might be a terrible tragedy," he said.

Dmitry Lovetsky / AP

"I would like to note that we are calling this not an incident, not a catastrophe, but a terrorist act," Poroshenko told the Dutch prime minister, Mark Rutte, in a phone call to express condolences, according to The New York Times.

The wreckage of Malaysia Airlines Flight 17

Dominique Faget / AFP / Getty

The area where the flight was lost has seen severe fighting between Ukrainian forces and pro-Russia separatist rebels in recent days, reports the Associated Press.